Testosterone could be partly responsible for crises in city trading.
(Cambridge University researchers discovered that testosterone levels were linked to the profit that male City of London traders made. The downside is that they can then become over-confident, and take bigger and bigger risks leading to huge losses. They recommend recruiting more women, but I would have thought that wouldn't help the testosterone levels of the remaining men at all. Just remember though, when a City trader makes a big profit or loss, they were just feeling a bit hormonal.)